This invention relates generally to optics and, more particularly, to optical elements utilized to diverge collimated or nearly collimated beams of radiant energy into a predetermined solid angle (e.g., 2.pi. steradians), or alternatively, to converge or collimate radiant energy from solid angle image fields.
Various applications in optics and the like require that a beam of radiant energy, such as that emitted by a laser, be diverged uniformly into a 2.pi. solid angle, or hemisphere. For example, remote optical controllers and similar such systems often require that a radiant energy beam be directed to an object or target whose location is not pin-pointed relative to the source of the beam, and may vary anywhere within a 2.pi. solid angle of the beam axis.
This divergence is usually accomplished utilizing so-called "fish-eye" or wide angle diverger lens systems. These systems typically comprise a plurality of negative lens elements, spaced apart from one another and aligned on a common optical axis. A beam of radiant energy which is incident on the system along the common optical axis is progressively diverged by each lens element, with the final divergence into the 2.pi. solid angle being effected by the last lens element in the system.
Because lens systems of this type are relatively expensive to manufacture and thus high in cost, they are impractical for use in many applications where substantial cost constraints exist. Additionally, since the beam is progressively diverged by each lens element in such a system, the last lens element must have a cross-sectional size that is relatively large in comparison to the initial beam size to accommodate the divergence effected by the earlier lens elements in the system. Thus, these systems can also be impractical for use in applications where the size and/or weight of the optical elements must be kept to a minimum.
In view of the above, it is a primary object of the present invention to provide an improved optical element capable of diverging a radiant energy beam into a predetermined solid angle.
Another object of the invention is to provide an optical element of the above-described type which is relatively inexpensive to manufacture and low in cost.
Another object of the invention is to provide an optical element of the above-described type which can be made relatively light in weight and relatively small in size in relation to the beam which it diverges.
Another object of the invention is to provide an optical element of the above-described type which is easy to mount and align within an optical system.
Still another object of the invention is to provide an optical element of the above-described type which, due to the principle of reversability, can be used in reverse to converge or collimate radiant energy from a solid angle image field.
Other objects of the invention will in part appear, and in part be obvious from, the detailed description which follows.